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LACP and Unidirectional Link Detection

All,

Does LACP support unidirectional link detection like PaGP does in desirable mode?

3 REPLIES

Re: LACP and Unidirectional Link Detection

Are you sure PAGP supports UDLD. The documentation I see on CCO contradicts that.

See below:

Unidirectional EtherChannels cannot support PAgP or LACP. To create a unidirectional EtherChannel, you must configure the EtherChannel "on" mode.

Ref Link: http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a008043580d.html

Hope it helps.

--Sundar

New Member

Re: LACP and Unidirectional Link Detection

I guess I worded my question incorrectly.

A PaGP etherchannel in desirable mode provides UDLD type functionality. Does LACP provide the same functionality? My guess is yes it does because LACP supports the automatic creation of etherchannels in an active/active or active/passive configuration.

I just can't find documentation to support this.

Re: LACP and Unidirectional Link Detection

Got it.

Yes, the functionality of LACP is very similar to PAGP excepting that LACP is an IEEE standard.

The following link from IEEE explains the inner-working of the protocol.

www.ieee802.org/3/ad/public/july98/jeffree_070798.pdf

Here's Cisco's explanation of LACP:

Link Aggregation Control Protocol (LACP) is part of an IEEE specification (802.3ad) that allows you to bundle several physical ports together to form a single logical channel. LACP allows a switch to negotiate an automatic bundle by sending LACP packets to the peer. It performs a similar function as Port Aggregation Protocol (PAgP) with Cisco EtherChannel.

Regards,

Sundar

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